The goal of this research project is to better understand the effects, and limitations, of cognitive factors in human autonomic classical conditioning. The major autonomic measures are components of the electrodermal response system. The principal experimental questions include the following: (1) Can nonattended verbal CSs elicit electrodermal conditioned response without the subject's awareness? This question will be addressed by presenting verbal CSs within the nonattended channel of a dichotic listening task. Special emphasis will be placed on cerebral laterality effects in the investigation of this phenomenon. (2) Do cognitive/autonomic dissociations occur during acquisition and extinction with "biologically prepared" contingencies and not with "biologically unprepared" contingencies? This question will be studied by simultaneously measuring cognitive and electrodermal changes on a trial-by-trial basis as a function of the "preparedness" of the CS-UCS contingency. (3) Can momentary changes in cognitive processing demands be measured during autonomic conditioning and be related to individual differences in autonomic conditioned responses? This question will be studied by developing a continuous secondary task for subjects to perform during autonomic conditioning. The subjects' performance on the secondary task will reflect the amount of cognitive processing capacity expended during different phases of autonomic conditioning.